To include the JDatePicker dependency in your project via maven you need to add the following dependency declaration in your project’s pom:
This will only work up to version 1.3.2. Later releases are not yet in the maven central repo. They can be downloaded from the sourceforge released files (http://sourceforge.net/projects/jdatepicker/files/Releases).
You may also get source versions of the project by checking out the specific tag you are interested in (see http://jdatepicker.svn.sourceforge.net/viewvc/jdatepicker/tags or http://sourceforge.net/scm/?type=svn&group_id=107962).